This core supports Projects' 1 - 4 by collecting long-term follow-up data for patients who have had hematopoietic cell transplantation (HCT) at the Seattle Cancer Care Alliance (SCCA), University of Washington or Seattle Children's under protocols developed at the Fred Hutchinson Cancer Research Center (FHCRC). The services of this core unit address several closely related areas: identification and management of late complications, data collection, database assembly and evaluation of the efficiency, accuracy, quality and utility of the data collection and the system in which the data are stored. We have developed several mechanisms to support this overall goal. 1) We will continue to collect long-term data focused on survival, therapy-related complications, and health relevant to the clinical research studies sponsored by this grant. This includes the retrospective cohort of patients currently in follow-up from previous studies and the prospective cohort of patients to be enrolled in studies described in Projects 1 - 4 . For this purpose, a system has been established to track and maintain contact with patients and referring physicians so that data can be collected at specified time points after treatment. 2) We will continue to assist investigators in obtaining information and biospecimens that are not routinely collected but are needed for individual research projects. 3) We will continue to identify barriers that interfere with long-term follow-up and develop methods to overcome these barriers. 4) We will continue to evaluate the research methods employed in data collection and database management, including the efficiency, reliability, validity and utility of the instruments used in the Long-Term Follow-up (LTFU) core. The data generated from this core unit will assist project leaders in the identification of late complications after HCT and help in the development of methods for improved management or prevention of these complications. The data could help to generate hypothesis-driven research concerning risk factors for late complications, the pathophysiology leading to late complications, and the development of methods for preventing or treating late complications after HCT.